 /*
 * ---------------- www.spacesimulator.net --------------
 *   ---- Space simulators and 3d engine tutorials ----
 *
 * Author: Damiano Vitulli
 *
 * This program is released under the BSD licence
 * By using this program you agree to licence terms on spacesimulator.net copyright page
 *
 *
 * 3ds models loader
 *  
 */

#include <windows.h>
#include <stdio.h>
#include <stdlib.h>
#include <conio.h>
#include <io.h>
#include "object.h"
#include "load_3ds.h"



/**********************************************************
 *
 * FUNCTION Load3DS(obj_type_ptr p_object, char *p_filename)
 *
 * This function loads a mesh from a 3ds file.
 * Please note that we are loading only the vertices, polygons and mapping lists.
 * If you need to load meshes with advanced features as for example: 
 * multi objects, materials, lights and so on, you must insert other chunk parsers.
 *
 * Input parameters: p_object = Pointer to the Object
 *					 p_filename = Filename of the object to load
 *
 * Return value: (char) 1 if the object was loaded correctly, 0 otherwise
 *
 *********************************************************/

char Load3DS(obj_type_ptr p_object, char *p_filename)
{
	int i; //Index variable
	
	FILE *l_file; //File pointer
	
	unsigned short l_chunk_id; //Chunk identifier
	unsigned int l_chunk_length; //Chunk length

	unsigned char l_char; //Char variable
	unsigned short l_qty; //Number of elements in each chunk

	unsigned short l_face_flags; //Flag that stores some face information

	if (p_filename=='\0') return(0);

	if( fopen_s(&l_file, p_filename, "rb") ) 
	{
        MessageBox(NULL,"3DS file not found","Spacesim",MB_OK | MB_ICONERROR);
		return (0);
	}

	while (ftell (l_file) < _filelength (_fileno (l_file))) //Loop to scan the whole file 
	{
		//getche(); //Insert this command for debug (to wait for keypress for each chuck reading)

		fread (&l_chunk_id, 2, 1, l_file); //Read the chunk header
		fread (&l_chunk_length, 4, 1, l_file); //Read the length of the chunk

		switch (l_chunk_id)
        {
			//----------------- MAIN3DS -----------------
			// Description: Main chunk, contains all the other chunks
			// Chunk ID: 4d4d 
			// Chunk Length: 0 + sub chunks
			//-------------------------------------------
			case 0x4d4d: 
			break;    

			//----------------- EDIT3DS -----------------
			// Description: 3D Editor chunk, objects layout info 
			// Chunk ID: 3d3d (hex)
			// Chunk Length: 0 + sub chunks
			//-------------------------------------------
			case 0x3d3d:
			break;
			
			//--------------- EDIT_OBJECT ---------------
			// Description: Object block, info for each object
			// Chunk ID: 4000 (hex)
			// Chunk Length: len(object name) + sub chunks
			//-------------------------------------------
			case 0x4000: 
				i=0;
				do
				{
					fread (&l_char, 1, 1, l_file);
                    p_object->name[i]=l_char;
					i++;
                }while(l_char != '\0' && i<20);
			break;

			//--------------- OBJ_TRIMESH ---------------
			// Description: Triangular mesh, contains chunks for 3d mesh info
			// Chunk ID: 4100 (hex)
			// Chunk Length: 0 + sub chunks
			//-------------------------------------------
			case 0x4100:
			break;
			
			//--------------- TRI_VERTEXL ---------------
			// Description: Vertices list
			// Chunk ID: 4110 (hex)
			// Chunk Length: 1 x unsigned short (number of vertices) 
			//             + 3 x float (vertex coordinates) x (number of vertices)
			//             + sub chunks
			//-------------------------------------------
			case 0x4110: 
				fread (&l_qty, sizeof (unsigned short), 1, l_file);
                p_object->vertices_qty = l_qty;
                for (i=0; i<l_qty; i++)
                {
					fread (&p_object->vertex[i].x, sizeof(float), 1, l_file);
                    fread (&p_object->vertex[i].y, sizeof(float), 1, l_file);
					fread (&p_object->vertex[i].z, sizeof(float), 1, l_file);
				}
				break;

			//--------------- TRI_FACEL1 ----------------
			// Description: Polygons (faces) list
			// Chunk ID: 4120 (hex)
			// Chunk Length: 1 x unsigned short (number of polygons) 
			//             + 3 x unsigned short (polygon points) x (number of polygons)
			//             + sub chunks
			//-------------------------------------------
			case 0x4120:
				fread (&l_qty, sizeof (unsigned short), 1, l_file);
                p_object->polygons_qty = l_qty;	
                for (i=0; i<l_qty; i++)
                {
					fread (&p_object->polygon[i].a, sizeof (unsigned short), 1, l_file);
					fread (&p_object->polygon[i].b, sizeof (unsigned short), 1, l_file);
					fread (&p_object->polygon[i].c, sizeof (unsigned short), 1, l_file);
					fread (&l_face_flags, sizeof (unsigned short), 1, l_file);
				}
                break;

			//------------- TRI_MAPPINGCOORS ------------
			// Description: Vertices list
			// Chunk ID: 4140 (hex)
			// Chunk Length: 1 x unsigned short (number of mapping points) 
			//             + 2 x float (mapping coordinates) x (number of mapping points)
			//             + sub chunks
			//-------------------------------------------
			case 0x4140:
				fread (&l_qty, sizeof (unsigned short), 1, l_file);
				for (i=0; i<l_qty; i++)
				{
					fread (&p_object->mapcoord[i].u, sizeof (float), 1, l_file);
                    fread (&p_object->mapcoord[i].v, sizeof (float), 1, l_file);
				}
                break;

			//----------- Skip unknow chunks ------------
			//We need to skip all the chunks that currently we don't use
			//We use the chunk length information to set the file pointer
			//to the same level next chunk
			//-------------------------------------------
			default:
				 fseek(l_file, l_chunk_length-6, SEEK_CUR);
        } 
	}
	fclose (l_file); // Closes the file stream
	return (1); // Returns ok
}
